My wife and I (+our baby) visited Kobkul's place this January and I have to say we had a Fantastic experience!
I'll point out several things that made our stay lovely and worth it:
The host: Kobkul is great! She was really responsive before arriving; while we stayed at her house she was extremely hospital and nice - preparing breakfast and coffee and guiding us with all the information needed. Every time we needed something - she was there for us, which made the stay really special.
The location: The flat is 30min walking distance to majority of points of interest in the city. If you take a tuk-tuk/Grab/Taxi it would be 5-10min based on the traffic. We love walking so that was no-brainer for us: ChinaTown, Khaosan road, temples - majority of sightseeing we did by walking. And of course - just in front of the place is the famous Thimsampai Pad Thai restaurant, where I believe the most delicious pad thai is made :) (+ the Michellin star restaurant just next to it).
The listing: It's what I believe a traditional (but renovated) Thai house with wooden floor, which makes it really cozy. We stayed on the last floor. Something worth noting is that there's one bathroom/toilet in the whole house which is shared; this creates an effort to go there when you're on the last floor, but after the 2nd day we really didnt mind it at all.
On the ground floor you have Kobkul's coffee shop, where she's also selling monks clothes - definitely give a try of the coffee she does!
In conclusion - we'll definitely be back and would recommend Kobkul's place to all our friends visiting Bangkok!